Concrete piers (or pier blocks) are commonly used to support structures such as dwellings, porches, decks, etc. A longstanding problem with concrete piers is that levelling is difficult during construction. A further problem is that the ground may move or settle over time, for example due to freezing and thawing.
U.S. Pat. No. 5,561,950 (Collins et al.) discloses an adjustable concrete pier that attempts to address this problem. This adjustable pier block is height-adjustable so that a deck, porch, structural beam, etc. can be leveled. This adjustable pier block can be also be re-adjusted if the ground has settled over time. This adjustable concrete pier has a threaded rod embedded into the concrete footing (concrete block). Although the basic idea is meritorious, there a number of shortcomings with this prior-art design. Firstly, the strength of this prior-art adjustable pier block is quite limited because the threaded rod is embedded directly in the concrete. The interface between the concrete and the threads of the threaded rod provides only limited strength. This design is vulnerable to failure, particularly under impact loading. Secondly, the range of adjustability of this prior-art adjustable pier block is limited as the top coupling can only be safely raised a certain amount before the coupling and threaded rod become undone or loose. A third design limitation of this prior-art pier block is that, since the threaded rod is embedded permanently in the concrete pier block, the pier block can only be used with that particular threaded rod. There is no ability to replace the threaded rod.
In view of these shortcomings, an improvement on this prior-art pier block would thus be highly desirable.